Carboxy-functional hydrolyzable silanes

ABSTRACT

Silanes of the formula (HOOC)mRSR&#39;&#39;Si(R&#39;&#39;&#39;&#39;n)Y3 n are made by adding unsaturated acids to HSR&#39;&#39;Si(R&#39;&#39;&#39;&#39;n)Y3 n or by adding mercapto carboxylic acids to alkenyl-Si(R&#39;&#39;&#39;&#39;n)Y3 n. For example, thioglycolic acid is added to vinyltrimethoxysilane in the presence of a free radical generator to give HOOCCH2SCH2CH2Si(OMe)3. The acids are used as adhesion promotors for silicon rubber.

United States Patent Inventor Gary E. LeGrow Midland, Mlch.

Appl. No. 888,939

Filed Dec. 29, 1969 Patented Dec. 14, 1971 Assignee Dow CorningCorporation Midland, Mich.

CARBOXY-FUNCTIONAL HYDROLYZABLE SILANES 6 Claims, No Drawings U.S.Cl260/448.2 B, 117/135.1 1nt.CI C07! 7/18, C23c 11/06 Field of Search260/4482 B [56] References Cited UNITED STATES PATENTS 2,563,516 8/1951Burkhard 260/4482 B 2,604,486 7/1952 Burkhard 260/4482 B PrimaryExaminer-Tobias E. Levow Assistant Examiner-Werten F. W. BellamyAttorneys-Robert F. Fleming, Jr., Laurence R. Hobey. Harry D. Dingmanand Howard W. Hermann hesion promotors for silicon rubber.

CARBOXY-FUNCTIONAL HYDROLYZABLE SILANES A primary utility for thesilanes of this invention is the use as additives for unvulcanizedsilicone rubber to promote the adhesion of the cured rubber to substratesuch a aluminum, steel and other metals. This use is described andclaimed in the copending application of Keith E. Polmanteer Ser. No.888,940, entitled Room-Temperature Vulcanizable Silicone Rubber WithUnprimed Adhesion," filed concurrently herewith. in addition the silanescan be used as intermediates in the preparation of silicone-alkydresins, which in turn are used for paint vehicles and electricalinsulation.

This invention relates to silanes of the formula (HOOC),,,RSRi(R",,)Y inwhich R is a hydrocarbon radical having a valence of m+l attached to thesulfur through an aliphatic or cycloaliphatic carbon atom, R is adivalent hydrocarbon radical, R" is a monovalent hydrocarbon ormonovalent halohydrocarbon radical, n is an integer from to 2, m is aninteger from 1 to 2, and Y is selected from the group consisting ofalkoxy radicals, alkoxy-alkoxy radicals, carboxyacyl radicals, andketoxime radicals of the formula ON C in which the unsatisfied valencesof the carbon atom are satisfied with monovalent hydrocarbon radicals orthe same divalent hydrocarbon radical, R, R, R" and Y being free of C-Caliphatic unsaturation.

The compositions of this invention can be prepared by two methods. Thefirst involves the addition of a carboxylic acid having alkenylunsaturation to a mercapto hydrocarbyl silane in which the SH group isattached to silicon through'a carbon atom. In carrying out this reactionif the acid is conjugated, for example, acrylic acid or methacrylicacid, care should be taken to avoid polymerization of the acid. This canbe accomplished by employing a base catalyst, such as sodium methoxide.Ultraviolet light or other free radical generators can be employed ifcare is taken to avoid excessive polymerization of the acid. In usingacids which are not conjugated, the best method is to employ freeradical generators, such as ultraviolet light, azo-bisnitriles andperoxide.

The second method involves the addition of mercapto carboxylic acids,such as thioglycolic acid to an alkenyl silane such as allylsilane. Thisaddition is best carried out in the presence of a free radical generatorsuch as azo-bis-iso-butyronitrile, peroxides or ultraviolet light. lnboth of the above methods the temperature of addition takes place fromroomtemperature to 70 C., depending upon the free radical catalystemployed, and the reactivity of the silane and the acid used.

The first reaction can be illustrated by the equation (HOOC)1"RCH=CH+HSRSi(R",,)Y (H OOC),,,RR"Si( li ;)Y ,,l ln carrying out this reactionone can use any acid having aliphatic unsaturation. These include acidssuch as acrylic, methacrylic,

and itaconic acid.

The mercaptosilanes employed in this reaction can by any mercaptosilanein which the sulfur is attached to silicon through a carbon atom such asthose having the structure HSOSL HS s s1, HSOCHmmSi, HSCHzSl, nswmmsi,nsomomOomomsx and I-ISCHzCH(OzHr) 011281 Thus it can be seen R can beany divalent or trivalent hydrocarbon radical attached to the sulfurthrough an aliphatic or cycloaliphatic carbon atom and can be anyradical such as methylene, dimethylene, octadecamethylene,cyclohexalene,

R can be any divalent hydrocarbon radicals such as methylene,dimethylene, trimethylene, octa-decamethylene, phenylene, tolylene,xenylene, naphthylene, ethylidine, isopropylidene and cyclohexalene.

R" can be any monovalent hydrocarbon radical free of aliphaticunsaturation such as alkyl radicals such as methyl, ethyl, isopropyl,octadecyl or myricyl; cycloaliphatic hydrocarbon radicals such ascyclopentyl, cyclohexyl or methylcyclohexyl; aryl hydrocarbon radicalssuch as phenyl, xenyl, tolyl, xylyl, naphthyl or anthracyl and aralkylhydrocarbon radicals such as benzyl, 2-phenylethyl, or Z-phenylpropyl. kR can be any halogenated monovalent hydrocarbon radical :free ofaliphatic unsaturation such as haloalkyl radicals such as chloromethyl,3-chloropropyl, bromoctadecyl, 3,3,3- trichlofopr pyl, chloroisopEpyTor2(perfluoroalkyl)- ethyl K radicals in which the perfluoroalkyl radicalis trifluoromethyl, perfluoroethyl, perfluoroisobutyl orperfluorooctadecyl; halocycloalkyl radicals such as bromocyclohexyl,chlorocyclopentyl or fluorocyclohexyl; haloaryl radicals such as 2,4-

dichlorophenyl, dibromoxenyl, alpha, alpha, alphatrifiuorotolyl,iodonaphthyl and tetrachlorophenyl and haloaralkyl radicals such as2(chlorophenyl)ethyl, p-

chlorobenzyl or 2(bromophenyl)-propyl.

For the purpose of this invention Y can be any alkoxy group such asmethoxy, ethoxy, isopropoxy, butoxy or octa-decyloxy; any alkoxyalkoxyradical such as betwmethoxyethoxy, betaethoxyethoxy, beta-butoxyethoxy,or -(OCH CH OCH any carboxy acyl radical such as formyloxy, acetoxy,propionyloxy, butyryloxy or octanoyloxy; or any ketoxime radical of theformula -ON=C in which the unsatisfied valences of the carbon atom aresatisfied with two hydrocarbon radicals (i.e. ON=CZ such as alkylradicals such as methyl, ethyl, isopropyl, dodecyl, or octadecyl,cycloalkyl radicals such as cyclopentyl and cyclohexyl; any arylradicals such as phenyl, naphthyl, and xenyl; any aralkyl radicals suchas benzyl, beta-phenylethyl, and beta-phenylpropyl; and any alkarylradicals such as tolyl, and dimethylphenyl; or the same divalenthydrocarbon radical Example l This example illustrates the first methodof preparing the silanes of this invention. Three hundred and ninety-twograms of 3-mercaptopropyltrimethoxysilane was added with stirring over aperiod of 2 hours to a solution of 0.25 g. of sodium methoxide in 144 g.of glacial acrylic acid. An exotherm occurred to a maximum temperatureof 72 C. during the addition. The water white product had the formula(Me0)=,Si(CH );,SCH CH COOH which had the following properties: n ofl.4609, of 1.12, visc. of 26.5 cs. at 25 C. and R observed of 02450..

Example 2 This example illustrates the second method of preparing thecompositions of this invention.

was established by nuclear magnetic resonance data.

Example 3 l, the following products are obtained. in the tables the fol-Two hundred and ninety-six grams of vinyl trimethoxysilane lowingabbreviations are used; Me for methyl, Et for ethyl and was added withstirring to a mixture of 184 g. of mercapto Ph for phenyl.

TABLE 1 Acid Mercaptosllane p I Product HOC(Ma) =CH,.. Ill/1e YHOOCCH(Me) CHQS C1 Sl(M8)(0N=CMe2)z Hs cH2s1 0N'=0Mez)2 HOOCCqH4GH=OHrHS CflH4Si(OMe)3 HOOCCgHrCH CH SCdLSKOMo);

([IllHz 1'19: HOOCCHCH SCHgCeHdCH)zSi(M8)z(OCaHn) HO OCOCHQCOOH. HSCHaCHoHt(CH2)2Si(O CaHla) HOOCCH: HOOCCH=CH2 1' 1!IIOOC(CH2)2S(ClighSiUh)(0000 115);

HS (CHz);Si(OOCC2H5)2 HOOCOH=CH2 HS(CH2)a(CFsCHzCH-2)Si(OMe)gI'IOOC(CI'I2)2S(CIIE)SS1(CIIZC1{ZCF3)(OMC)2 HS (CH2)z(C1CtH4) S 1(OMe) 2HO O C (CH2)a S (0112):;8 1(Col-I4Cl) (0M0); HS (CH2)a(BrCoH1o) S1(0M6)zHO O C (CH2)2S (CHzhSKCaHmBr) (OMB) 2 HS (CHz)3(CuH5CHzCHz) Si(OMe)g HOO C(CI'I2)2S(CHQ)IS1(CIIZCI{2CHI'I5)(OMG)2 acetic acid containing 0.1 g.of azo-bis-isobutyronitrile. The Example 7 mixture exothermed, but thetemperature was not allowed to When the following acids are reacted withthe following exceed 50 C. On complete addition a clear, colorlessproduct mercapto hydrocarbylsilanes employing azo-bis-isobutrowasobtained having the fo r n1ula HOOCCH= S(; H CH nitrile as a catalystthe following products are obtained.

TABLE 2 Acid Mercaptosllane Product HO O C C uiHgoCH=CHL H S CmHaa SKOEL) 3 HO O C CHHH! S CIBHMS 0E0: 1100 CCoUwCH==CIlz Hs CuI-ImSKOCIhCHOMch 1100CCBIJItoCHzCIIzSCoHmSl(OCIiQClfiOMO)a 11000011 011 x111 r-'\ 2a 11s ClIrSKCnHao) (who 0,1110 1100c cumsclnsucmlm) (ON:=C 0mm):

L .l L ..J

Same as above IIS(CII2)3SKCH2CH2CIIQClXOOCGBIIH)?HOOC(CHz)as(CH2)351(01120112011261) (00 051 11):

HSCH2Si(OMe)2(OC1aHa7) I H00 H00 S SOHgSi(OMc)z (OC1aH;n)

HOOCCHrOH=OHg HS CH2Si(CrH4CF )(ON=C'Ph2)2 H0OC(CH2)3SCHzSKGaHgCFa)(0N=QLOMeh and having the following properties: n 1.4635, Th t which is C am is: (14 1.150 RD observed 297 v i V I 1. A silane ofthe formulaExample 4 R is a hydrocarbon radical having a valence of m+lEighty-eight grams of "lethally! "imelhoxysilane added which is attachedto the sulfur through an aliphatic or with stirring to 46 g, ofmercaptoacetic acid containing 0.05 g. i h ri carbon atom, ofazo-bis-butyronitrile. The mixture was not allowed to heat R i a di l hd b n di al, above C. The product was a colorless fluid having the for-R" i a on lem hydrocarbon or monovalent mula HOOCCH SCH ClKMe)CH Sl(OM6)having the fOl- 50 halohydrocarbgn radical,

lov iggpropertiesz mi 1.4547, dfi 1.107, and R observed n i an integerfr m 0 to 2,

4 m is an integer from 1 to 2, and

Y is an alkoxy radical and alkoxyalkoxy radical, a carboxyacyl radicalor a ketoxime radical of the formula ON C in Seventy-four grams of vinyltnmethoxysrlane was added 5 5 hich the unsatisfied valences of thecarbon atom are satisfied Example 5 dropwise with stirring to a solutionof 75 g. of thiomalic aci in with monovalent hydrocarbon radicals or thesame divalent 150 g. of methanol containing 0.05 g. ofazo-bis-isobuhydrocarbon radical R, and y being f f tyronitrile.Irradiation with an infrared lamp caused evolution anphatic Smut-anon ofheat a maximum The methanol solve! was 2. A silane in accordance withclaim 1 which is of the forremoved at reduced pressured leaving a highlyviscous l HOOCCH CH s(C]-[ SKOCH h Pmcluct having the of 4485 and Show"y nuclear g 3. A silane in accordance with claim 1 which is of thefornetic resonance spectra to have the formula mula H0OCCH S(CH,)Si(OOCCH,

4. A silane in accordance with claim 1 in which the formula H OCCHSCH CHSi OM O noocc -i,s cH, ,si ocH,),. HQQ CCH H V g w 5. A silane inaccordance with claim 1 which IS of the for- Exam le 6 mula HOOCH SCHCH(CH )Cl-l Si(OCH p 6. A silane in accordance with claim 1 which is ofthe for- When the following acids are reacted with the following mulamercaptosilanes in accordance with the procedure of example W

2. A silane in accordance with claim 1 which is of the formulaHOOCCH2CH2S(CH2)3Si(OCH3)3.
 3. A silane in accordance with claim 1 whichis of the formula HOOCCH2S(CH2)2Si(OOCCH3)3.
 4. A silane in accordancewith claim 1 which is of the formula HOOCCH2S(CH2)2Si(OCH3)3.
 5. Asilane in accordance with claim 1 which is of the formulaHOOCH2SCH2CH(CH3)CH2Si(OCH3)3.
 6. A silane in accordance with claim 1which is of the formula